Hand-held marking devices that are driven, for example, by a battery powered motor and are capable of drawing selected design such as a circle, are known in the art. Patents that have been granted on this type of device include the following:
U.S. Pat. No. 3,297,003 issued Jan. 10, 1967 to B. S. Benson, entitled "Pencil or Pen With a Moving Point";
U.S. Pat. No. 209,112 issued Oct. 31, 1967 to H. A. Plassman and F. H. Sedris; and
U.S. Pat. No. 3,997,972 issued Dec. 21, 1967 to J. V. Jaunaraja.
Non-powered marking devices in the field of the present invention include U.S. Pat. No. 2,390,226 issued Dec. 11, 1945 to J.P. Smith; U.S. Pat. No. 2,805,475 issued Sept. 10, 1957 to H. K. Adams; and U.S. Pat. No. 2,095,116 issued Oct. 5, 1937 to J. S. Albin.
U.S. Pat. No. 3,297,003 to Benson discloses an elongated housing having a bore that contains a marking member positioned between a surface to be marked surface at one end of the housing. The marking member is coextensive with a movable eccentric. A circular narrowed portion, or fulcrum, positioned between the eccentric and the surface to be marked pivotably supports the marking member. A guide means having a wall forming a noncircular opening contacts the marking member during its rotation and confines the marking member so as to produce noncircular decorative markings to the surface to be marked.
It is apparent that the Benson invention reveals several problems on its face. One is that the tip of the marking member is constantly changing angle with the marking surface. As the operator moves the device along the surface to be marked, the tilt of the marking member as it rotates will cause alternate retarding and sliding forces of the marker member tip relative to the paper and the movement of the device by the operator. Another problem is that the length of the marking member can only be a ball-point pen or an analogous instrument because there is no provision for adjusting the length of the marking member in the housing. This requirement eliminates graphite, colored, felt tip, and other such marking members. Another problem is that a marking member of only one size and length can be mounted in the housing. Provision for replacement of a worn-out ballpoint pen with a new pen is not set forth in the disclosure.